Selective telephone call mechanism.



No. 766,94 5. PATENTED AUG. 9, 1904. H. I. HAWXHURST. SELECTIVE TELEPHUNE GALL MEGHANISM.

APPLIUATION FILED SEPT. 5, 1902. N0 MODEL. 2 SHEETS-SHEET l.

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v H. I. HAWXHURST.

SELEGTIVE TELEPHONE GALL MEUHANISM.

APPLICATION FILED SEPT. 5, 1902.

H0 MODEL. 2 SHEETS-SHEET 2.

UNITED STATES Patented August 9, 1904,

PATENT OEEICE.

SELECTIVE TELEPHONE CALL NIECHANISNI.

SPECIFICATION forming part of Letters Patent N0. 766,945, dated August 9, 1904.

Application filed September 5, 1902. Serial No. 122,163. (No model.)

`Tod/ZZ whom, it may concern:

Be it known that I, HENRY lvINs HAWK- HURs'r, a citizen of the United States, and a resident of East Oakland, California, have invented certain new and useful Improvements in Selective Telephone Call Mechanism, of which the following is a speciiication, reierence being had to the accompanying drawings, forming a part thereof.

The purpose of this invention is to provide an improved device for use on a party-line telephone to prevent the calls from the central exchange being heard or received at any oi' the telephone-stations on the party-line eX- cept the one which is wanted.

It consists in the employment of devices by which the oscillating or rotating switch at each station on the party-line is caused to close the circuit for ringing the bell at that station only when the switch halts after a movement differing for each station and devices for actuating' the switch by steps by means of an electromagnet in the line-circuit extending` to the central station and controlled by the central operator, so that the amount oi' movement or number of steps communicated to the switch will be made to correspond to the adjustment of the instrument whose call is to be sounded.

It consists, further, in a structure by which the line-circuit for energizing' the electromagnets affords the current also for ringing the bell at the station which is called.

It further consists in the particulars of conf struction andoperation, which are set out inl the claims.

In the drawings, Figure 1 is an elevation oi' the mechanism constituting my invention in its case, which is shown cut in vertical scction, the operating parts being shown in the position oi' rest. Fig. 2 is a similar View showing the parts in the position of ringing the bell at a particular station on the partyline. Fig. 3 is a section at the line 3 3 on Fig. 2. Fig. 4 is a detail section at the line 4 4C on Fig. 2. Fig. 5 is a diagrammatic view l showing' the arrangement of the circuits.

The structure whichI employ in my invention is designed to be assembled and mounted in a suitable case having four binding-posts l 2 3 4f, and it is adapted to be used in connection with any telephone-bell by disconnecting the wires 5 and 6 i'rom the binding'- posts 9 and 10 on the telephone-bell 11 and connecting the saine wires at binding-posts 1 and 2 of my device and thenextending wires 7 and 8 from binding-posts 3 and 4 of my device to the posts 9 and 10 of the telephone bell. The electromagnet and other mechanism oi` my device are thus interposed in the telephone-bell circuit, as will be understood from the following' description.

12 is an electromagnet mounted on the back plate 13 oil the case, having its coils connected at one end by the wire 11i, running' from the "`binding-posts 1, and from the other end by the wire 15, running to the bridgesplate 16, which connects the bindingposts 2 and 3. The magnet is thus always in the main line oi' circuit and is energized whenever thatcircuit is closed by the button or switch device at the central station. rl`he magnet-armature 17 is suitably pivoted upon bearings insulated by being mounted upon the wooden back plate 13 and is provided with a spring-pawl 18, which engages the ratchet-teeth 19 of an oscillating' switch 20, said switch being suitably pivoted on a bracket 21, insulated by being mounted on the back plate. The oscillating switch has beside the ratchet-teeth 19 a series oi detentteeth 22, and a light gravity detent-dog 23 is provided, suitably pivoted and insulated, to hold the switch at any position to which it may be moved by the feed-pawl on the armature-lever engaging the ratchet-teeth. The switch is weighted at one side, as seen at 2li, and a stop-pin 25 is provided in position to arrest its rotation in the direction in which the weight 24 would tend to rotate it, the action of the iced-pawl on the armature-lever being to swing it away from that position, to which thereupon the weight tends to return it. From the binding-post 1 the wire 26 extends to the bearing oi the oscillating switch, and on the periphery or' the switch there is mounted an insulating-segment 27, in the edge oi which there is, however, a metallic inset 28, which is connected with the metallic substance of the switch, and on the back plate there is mounted a switch-lcver 29, pivoted to the back plate in line with the center oi' the switch, carrying a IOO g which extends in a curve corresponding to the path of' a contact-abutment 35 on a momentum-wheel 36, which is mounted in a bracket 37, insulated by being mounted on the back plate. This momentum-wheel 36is weighted partly by the abutment 35, but additionally, if necessary, by other means, so that it normally assumes a certain position and is provided with a finger 38, which at the normal position of the wheel upholds the detent-dog '23 out of engagement with the detent-tooth 22 of' the oscillating switch 20. The armature-lever arm 17 has a finger 39, which encounters an abutment 40 near the center of the momentum-wheel as the armature is drawn toward the magnet-poles upon the energizing of the latter and upon such encounter throws the momentum-wheel around in direction to take the finger 38 away from under the detent-dog and allow the latter to drop onto the periphery of the oscillating switch and do its work in detaining the switch as it is actuated step by step by the pawl 18 on the armature-lever. The mass of the momentum-wheel is calculated to be such that it cannot recover from the impulse which it receives from the armature-lever finger' 39 so as to return to normal position in the short interval between successive feed movements of the pawl 18, so that the detent-dog will be free to operate as a detent so long as the energizing impulses of the magnet recur with rapidity; but upon a halt, due to holding down the buttonwhich closes the line-circuit through the magnet, thus maintaining the magnet energized and the armature in proximity to its poles, the momentum-wheel will recover its position so far as permitted by the finger 39,

which will be encountered in the recovering` movement of the wheel by the abutment 40, the position of' these parts being such that the wheel is stopped before its finger 38 reaches and lifts the detent-pawl. At this position of the momentum-wheel the abutment 35 is in contact with the spring-finger 34. Fromthe bracket 37, in which the momentum-wheel is mounted, electrical connection is made by the spring-plate 41 to the binding-post 4. If now the oscillating switch is actuated the necessary number of steps to bring it to a halt at a position at which the contact-piece 28 is in contact with the spring-finger 29, abranch circuit will be closed from the binding-post 1, through the oscillating switch 20, segmentplate 30, post 31, spring-finger 32, momentumwheel 36, bracket 37, and spring-plate 41, to the binding-post 4, thence to the bell by the wire 7, back by the wire 8 to the bindingpost 3, thence by bridge-plate 16 to the binding-post 2, and thence to the line.

If the.

number of step movements which the armature receives by a corresponding number of rapidly successive depressions of' the button at the central station is more lor less than the number necessary to halt the oscillating switch at the point to make contact with the springfinger 28, the bell will not ring, because if the number of' steps is deficient the contactpiece 28 will not reach the spring-finger 29, and if it is more than sufiicient said contactpiece will be carried past said finger so quickly that a single tick of the bell at the most will be all that will be heard and no continuous ring which will be understood to constitute the signal. Even such tick will not be caused unless at the same instant the spring-finger 32 is *in contact with the abutment 35, and .this will seldom happen, because the movement of the wheel 36 being caused by a blow ofthe finger 39 on the abutment 40 said wheel will be driven ahead and the abutment 35 will have passed the range of contact with the finger 32 by the time the feeding stroke of the pawl is finished-and the oscillating pawlhalts even in the interval of' the rapidly successive strokes. It will be seen, therefore, that by setting the switch-lever 29 at the several stations all at different positions, each position corresponding to a possible halting-place of' the contact-piece28 on the switch 20-that is, corresponding each to a certain number, but each to a different number of strokes or feeding impulses of magnet-armaturef-each station will receive its own signal only.

For convenience in assembling parts I make the connections to the binding-posts 1, 2, 3, and 4 lby means of spring-ngers upturned from'brackets 1, 2, 3, and 4, respectively, mounted on the back plate 13, the several connections mentioned as going to the binding-posts being, in fact, carried to these brackets and the spring-lingers of the brackets being encountered by the inner ends of the binding-posts or screws which secure them, or in the case of brackets 2 and 3 by the bridge which connects said posts when the boX or case on which the binding-posts are mounted is forced into position around the back plate 13 andthe mechanism mounted thereon. This makes it possible at any time to remove the four side walls and cover of the case, leaving the mechanism exposed upon the back plate and accessible from all sides for examination or adjustment.

I claim- 1. Aselective call mechanism for party-line telephone, comprising a main-line circuit; an electromagnet in the main-line circuit at each ofI the several stations; a secondary or local circuit at each station; a call or signal device operated in such local circuit by the closing of the same; a switch in the secondary or local circuit for closing the same, said switch being adapted to stand normally at and to return to open circuit position, "the contact- IOO IIO

pieces with which said switches respectively cooperate in the several circuits being at different positions relatively to the open-circuit position of the switch; mechanism operated by the electromagnet at each station for moving the switch step by step at successive impulses of the magnet; a device for automatically locking it after each' step, and a device line telephone, comprising a main-line circuit extending to all the stations; an electromagnet in such circuit at each station; a secondary or local circuit at each station; a call or signal device operated in such local circuit by the closing of the same; a switch in each such local circuit which normally stands at and tends to return to open-circuit position; a contactpiece with which such switch cooperates to close the circuit at one position in the range of movement of the switches, said contact-pieces in the movement of such circuit being at different positions relatively to the normal or rest positions of the switch; a pawl-and-ratchet device operated by the electromagnet at each station for moving the switch step by step at successive impulses of the magnet; a detentpawl for locking it after each step; a pivoted element which normally stands at a position of stable equilibrium, said element having means which at said position of stable equilibrium holds the detent-pawl out of action, the pawl-operating mechanism having connections by which at each step said element is driven from said position of stable equilibrium, said connection beingl such as to permit said element to move a greater or less distance according to the force of the blow by which it is thus driven, and to prevent its return to said position until the pawls feeding action is reversed.

3. A selective call mechanism for a partyline telephone comprisingl a main-line circuit, electromagnets in said circuit at the several stationsrespectively; a secondary or local circuit at each station; a call or signal device in each such local circuit; a switch in each such local circuit which normally stands at, and tends when displaced and released to return to, open-circuit position; contact-pieces at the several stations for cooperating with the switches respectively, at the different positions relative to the rest or open-circuit positions of the switches; mechanism for displacing the switches step by step through the whole range of contact positions, said mechanism comprising devices actuated by successive impulses of the magnet as the mainline circuit is successively opened and closed, and constructed to hold the switch at the posi- 4tion attained at each impulse until the circuit is opened; the local circuitcomln'ising a pivoted element which normally stands at a position of stable equilibrium; an arm actuated by the magnet-armature upon the impulse of the magnet arranged to displace said element from its position of stable equilibrium when the switch-operating movement is made; and a contact-piece for closing the local circuit through said element which is located so as to make contact for such closing at the position at which said element is held displaced while the switch is also held displaced.

In testimony whereof I have hereunto set my hand, in the presence of two witnesses, at East Oakland, California, this 12th day of June, A. D. 1902.

HENRY IVINS HAVXl-IURST.

In presence of-- ASA V. MENDENHALL, R. B. Goonsnm.. 

